Study design and data sources
This study utilized summary-level data from published studies and databases and all genetic data can be obtained through summary data of Genome-Wide Association Studies (GWAS), available athttps://gwas.mrcieu.ac.uk/ . Therefore, ethical approval from the institutional review board is not required for this research.
We conducted a two-sample Mendelian randomization (MR) analysis to assess the causal relationship between telomere length and the quantity and function of lymphocytes and their subsets. The summary Genome-Wide Association Study (GWAS) results for telomere length were derived from 472,174 genetically well-characterized adults in the UK Biobank (UKB). Telomere length was quantified as the relative telomere-to-single-gene-copy ratio, and the genetic variations in telomere length GWAS were adjusted for age and sex(12). The GWAS data for the quantity of lymphocytes were obtained from a genetic study focusing on multiple immunological traits in a European population of 7,313 individuals, which identified complex genetic regulation of immune cells(13). Further details regarding the GWAS summary data for telomere length and the quantity and function of lymphocytes can be found in Table S1.